1, Confirm whether the camera battery and SN match? Currently both the YI 4K and YI 4K plus camera are compitable with AZ16-2 and AZ16-1, thus a 3rd party battery could have compitable issue with the camera.
2, Make sure the camera firmware is the latest version.
3,Make sure the camera is not placed under an extreme cold enviroment.
4, The battery level may take a few moments to settle at one value as the camera is first powered.
5, Make sure to charge the battery completely and do not remove the battery while charging.